The invention relates to an arrangement in connection with a belt drive device which comprises two continuous drive belts arranged to be operated by means of drive rollers which to travel around stretching rollers as continuous and adjacent loops at a distance from each other and which are arranged to be pressed by means of press rolls against the opposite surfaces of a cable or the like to be drawn. Adjustment of the stretching roller of the belt drive device is provided by an adjustment means which effect a dead axle of the stretching roller.
At present, belt drive devices mentioned above are commonly used in cable production lines, for instance. Flat transmission belts, i.e. belts whose both surfaces are smooth, are commonly used as cable driving belts, for example. Drive belts in which the surface that is being pressed against the cable is shaped in a suitable manner are also used in the field.
The tightness of drive belts must be adjustable as required by the process. In other words, the belts must have a correct tightness during each process, The tightness of the belts is adjusted automatically by hydraulic or pneumatic cylinders, for example. The belt must also be prevented from slipping off the wheel. This can be performed by adjusting the axial angle of the stretching roller with respect to the direction of movement of the belt. The adjustment of the axial angle of the stretching roller has previously been performed by stopping the belt drive device for the adjustment, since the adjustment must be performed in a danger area. The adjustment of the prior art has been performed by winding eccentric sleeves arranged between a bearing arranged inside the stretching roller and the axle. It is to be noted that, for reason of safety, the arrangement cannot be used when the shelters are opened.
A drawback of the prior art is that the effect of adjustment is not immediately visible and, commonly, readjustment is necessary. In that case, the drive belt must be stopped to enable additional adjustment to be performed. These procedures must sometimes be carried out several times consecutively. A further problem occurs and if the adjustment is performed without a cable, whereby the rotational force caused by the torsional movement of the cable starts moving the belts when the device is then run with a cable. The belts move in such a manner that the top belt moves in one direction and the lower belt in the other direction. This also results in stopping the drive device, readjusting, restarting, etc.
An object of the invention is to provide an arrangement by which the drawbacks of the prior art can be eliminated. This is achieved by the arrangement of the invention, which is characterized in arranging the adjustment means on the side of the opposite end of the axle with respect to the stretching roller.
Above all, an advantage of the invention occurs whereby adjustment can be performed considerably faster than in the prior art. This is due to the adjustment of the axial angle of a stretching roller being performed while the drive belt device is running and the stretching roller is rotating. The adjustment of the axial angle of the stretching roller can thus be performed while the device is running. Performing the adjustment is perfectly safe since the shelters need not be opened and no procedure needs to be performed in the danger area. A further advantage of the invention is that it is simple and inexpensive to implement. Compared with the prior art, implementation causes no considerable extra costs.